If one asks for a hash table, one should not get a weak hash table unless one explicitly asked for it. MAKE-EQ-HASH-TABLE and MAKE-EQV-HASH-TABLE currently confusingly yield strong hash tables, as a consequence of which only a small fraction of their uses in MIT Scheme actually needed key-weak hash tables, while for a much large fraction, using key-weak hash tables was either confusing or incorrect. We can't change the semantics of these two procedures immediately, however, because what they do now is what they have been documented to do.